Flooding also caused a train to derail at Watford Junction in Hertfordshire, causing delays in and out of Euston.

Transport for London (TFL) is warning the District and Piccadilly lines will be much busier than usual, along with a number of key stops:

District line

Piccadilly line between King’s Cross St. Pancras and Hammersmith

Bakerloo line between Paddington and Embankment

Aldgate East

Baker Street

Earl’s Court

Edgware Road

Euston

Farringdon

Gloucester Road

Hammersmith

King’s Cross St. Pancras

Liverpool Street

Marylebone

Paddington

Shepherd’s Bush

Tower Hill

White City

Commuters using stations between Hammersmith and Edgware Road via Shepherd’s Bush Market are being told to take alternative routes as they may not be able to board trains and to expect buses to be busier than usual.

The union is angry over what it calls “heavy handed and aggressive management”, including claims that staff toilet breaks have been timed on a stop watch.

“This dispute is about the basic issues of protecting working conditions of our members and defending agreements from attempts to drive a coach and horses through them,” RMT General Secretary Mick Cash said. “The management are out of control and the anger at their failure to follow procedures has boiled over.”

But London Underground has rejected the union’s claims.

Steve White, Operations Director for London Underground, said: “We completely understand that sometimes drivers need to take a break during their driving duties to go to the toilet.

“But it has become clear that a minority are taking breaks of an hour or more and calling them toilet breaks. This has a direct impact on customers, with some trains being cancelled, and also on their fellow drivers who are having to cover for them.

“The suggestion that we are timing toilet breaks and asking intrusive questions is absolutely not true. That would be neither dignified nor reasonable. We are trying to support our staff – offering help through our Occupational Health team if a driver has health issues which requires them to take long breaks.”